The proposed investigation seeks to examine the role of sexual conflict about condom use in the association between substance use and HIV risk behavior among young men who have sex with men (YMSM) in New York City (NYC), as sexual conflict is thought to be a major mechanism of the association between substance use and HIV risk behavior. We will undertake quantitative and qualitative secondary data analyses and conduct a pilot project of the proposed expressive writing intervention, guided by the following three aims: (1) Test the proposed model and explore the extent to which the mechanisms of expressive writing's effects are relevant to sexual conflict and its association with HIV risk behavior among YMSM; (2) Utilize the evidence gathered in Specific Aim 1 to develop the writing instructions and protocol for the expressive writing pilot study (Aim 3); and (3) Conduct a feasibility and acceptability pilot of the writing instructions and project protocols among substance using YMSM. To achieve these aims, the first phase of the project involves secondary data analyses of data from three existing studies (two of which were NIDA-funded studies). These analyses will determine the role of the known mechanisms of expressive writing's effects in sexual conflict about condom use and the effects of conflict on HIV risk behavior and substance use. The second phase of the project involves utilizing the findings of these analyses to develop an expressive writing intervention. Finally, in the third phase of the project, we will conduct a feasibility and acceptability pilot project with 20 HIV-, substance usin, and sexually risky YMSM (18-29 years old). For the pilot project, we will utilize venue-based sampling to recruit a diverse sample of YMSM, who will complete a baseline assessment, three sessions of expressive writing, and a follow-up assessment one month after the writing sessions end. Assessments will include measures of sexual conflict, substance use, sexual risk, and feedback on the writing sessions as well as analyses of retention and intervention acceptability. Pilot data will be analyzed and results will inform the revision of the proposed model and the development of a larger-scale expressive writing intervention designed to intervene upon sexual conflict about condom use. PUBLIC HEALTH RELEVANCE: The findings of this study will facilitate a more nuanced understanding of the mechanisms underlying the association between substance use and HIV risk, which will, in turn, inform prevention and intervention efforts. Specifically, the findings wll inform preventions, interventions, and treatments designed to decrease substance use (and the negative effects of substance use), decrease HIV risk behavior, and to disrupt the association between substance use and HIV risk behavior. Further, this study will develop a highly portable, affordable, and easy- to-implement intervention modality that could be used across a variety of settings.